Air compressor from PTO... need CFM for sand blasting

Gary Cotz · Dec 5, 2016

It seems that you have to have about 9+ CFM to do any serious sand blasting. Harbor Freight has the pumps, just gotta figure out the way to get the PTO hooked up and a way to shut off the air intake automagically when the tank is near full. Anybody done this sorta thing before?

Shaneard · Dec 5, 2016

You need a Schramm Pneumatractor or tow behind. I bought this tractor about 8 years ago for cheap and the tow behind a few years ago for cheaper. They both have the same engine and are 6 cylinders, the front 3 are the engine and the back 3 are the compressor. They are both 160 CFM, yes, one hundred sixty CFM.

rustyshakelford · Dec 5, 2016

Don't know where you got your cfm from but that'll be a pretty small blaster. I would recommend buying a used tow behind or used 30 gallon gas compresser usually used by tire change companies. They are 20+ cfm and even that can be on the small side. The one I ordered is 29 cfm and I'm hoping I can get some stuff blasted ok

Brett

Big Barn · Dec 5, 2016

I agree with the others about a tow behind for the money. My 5HP shop compressor puts out 23 CFM and it's MINIMAL for my sand blast cabinet.

Terry

tcartwri · Dec 5, 2016

Gary Cotz said:
It seems that you have to have about 9+ CFM to do any serious sand blasting. Harbor Freight has the pumps, just gotta figure out the way to get the PTO hooked up and a way to shut off the air intake automagically when the tank is near full. Anybody done this sorta thing before?

You're missing a zero...

aarolar · Dec 5, 2016

tcartwri said:
You're missing a zero...

That's funny right there...

Industrial Toys · Dec 5, 2016

Isn't 187 kind of the standard basic CFM for a tow behind? What most pros use. That tractor/compressor is neat!

sd455dan · Dec 11, 2016

Have to agree with everyone else on this.

Even using really small sandblasting units,- i have the 110 lb. Harbor Freight tank style and power it with two 5 hp 60 gallon Ingersol Rand compressors, which combined put out just over 22cfm at 90 PSI.
If running the blaster more than a few minutes the pressure drops down to about 55psi. It works but really does need more cfm. Sandblasting really does require a lot of CFM

That 1/2 tractor 1/2 compressor really is NEAT and bet it works great for sandblasting

BHD · Dec 11, 2016

there are built in unloaders in some compressors the unloader is in the head of the compressor, and then some unloaders are just in the air line before the tank, and they dump the air and not put it in the tank at a preset pressure in the tank,

As far as the hook up to the tractor use a PTO shaft,

This is a set up I came up with, the compressor was off a old air powered beet thinner, (they were a failure from my understanding), I contacted the current company that has the rights to the compressor, and got information on how to set up and use the built in unloaded,

the small compressor on the truck was made from parts of a few different compressors I had a pump from one a tank from another, and add the gas motor, and a in line unloaded, with a kick down for the throttle. (bought from amazon the unloader)

CCWKen · Dec 12, 2016

I have an old Sulair 160 for large blasting jobs. It uses a 4-cyl. Chevy engine to drive a twin-screw compressor. I run the air to a 20 gallon tank so I can better control the pressure with a regulator and a filter/drier. From there it goes to my 300lb. pressurized media tank. When I'm blasting car body sheet metal at ~40psi, it barely comes off its idle speed.

digger doug · Feb 7, 2017

First thing, look on google for an air usage chart.
All the sandblasting outfits have them, Empire comes to mind.

Then work from that chart to figure out what compressor size you need.

I built one that ran off the PTO like pictured above, I get 200 CFM.

I then purchased a work truck with a engine drive one on the back, it is
a grimmer Schmidt 1/2 engine affair, put's out 150 cfm, and runs great
Who would think a ford 302 v-8 could run so smoothly on 4 cylinders ?

BukitCase · Feb 7, 2017

"Who would think a ford 302 v-8 could run so smoothly on 4 cylinders ?"

As long as it's the RIGHT 4 cylinders - might "lope" a bit if you were to make one that used all 4 firing cylinders in order, then all 4 compressor cylinders

My local tire guys have their ag/industrial trucks fitted with those small-block Ford compressors - when they came out and replaced all the tires on my 580B I found out how LOUD they are, but they sure make my 5 horse 23cfm look like a wimp... Steve

RNeumann · Feb 7, 2017

The CFM required is in direct relation to the media and orifice size and pressure used. If you have a small orifice and fine media 9 CFM MAY work.
Now to the second part of the question. The easiest way to deal with the constant pressure build-up is to dump it with a pressure sensitive valve. That way the pump and tractor can just keep going. The second idea would be an electric clutch between the PTO and pump (like the AC on you car or truck). I'm guessing the clutch solution would be more expensive.

digger doug · Feb 15, 2017

Bukitcase,
Odd that they were so loud.
Mine has a normal muffler, and it kind of just hums along nicely.

BukitCase · Feb 15, 2017

Doug, when I think back it seems like theirs was only loud when the compressor half kicked in - maybe it didn't have a breather on the compressor inlet?

Dunno, too long ago and at the time I'd just got my 580B and was more concerned with gettin' enough traction to do the push-out below my shop ('bout 800-900 yds of material moved with 3ph and Gannon box on the back)... Steve